A DNA microarray, or genome chip, may include hundreds of thousands of DNA probes. DNA probes may include a known DNA sequence which may be used to recognize longer, unknown DNA sequences. The recognition of sample DNA by the set of DNA probes on a glass wafer (or chip) takes place through the mechanism of DNA hybridization. When a DNA sample hybridizes with an array of DNA probes, the sample will bind to those probes that are complementary to a target DNA sequence. By evaluating to which probes the sample DNA hybridizes more strongly, it can be determined whether a known sequence of DNA is present or not in the sample DNA.
The DNA microarray may be fabricated by a high-speed robotic system, generally on glass but sometimes on nylon substrates. A large number of DNA probes may be produced on a chip using photolithographic fabrication techniques and solid-phase chemical synthesis.